Antibiotic prophylaxis for patients with hydrocephalus shunts:a survey of pediatric dentistry and neurosurgery program directorsGeorge Acs, DMD, MPH Elise Cozzi, DMD

Abstract

A survey of antibiotic prophylaxis recommendations for patients with hydrocephalus shunts was sent todirectors of advanced programs in pediatric dentistry and neurosurgery. Recommendations were sought forpatients with ventriculoperitoneal (VP) or ventriculoatrial (VA) shunts who were to receive dental care. respondents believed that shunt infection (SI) was related infrequently to dental procedures. Pediatricdentists believed that 5.2% of infected VA shunts were related to dental procedures, while neurosurgeonsbelieved the rate to be 3.0% (P < 0.05). There was no difference in perceived risk for VP shunts. Except for theequal risk associated with extractions, pediatric dentists were significantly more likely than neurosurgeons torecommend chemoprophylaxis for patients with VA shunts undergoing invasive dental procedures (P 0.05). They were more likely to agree with neurosurgeons when VP shunts were involved. Except for the equalrisk associated with dental prophylaxis, pediatric dentists and neurosurgeons believed VA shunt patientswere at greater risk for SI than VP shunt patients (P < 0.05). Pediatric dentists were significantly more likelyto ascribe SI to streptococcal organisms, and recommended penicillin for prophylaxis for both VA and VPshunts (P < 0.01 and 0.025, respectively). Although neurosurgeons believed that staphylococcal organismswere most likely to be responsible for SI (P < 0.001), 60% still recommended using penicillin for shuntprophylaxis following dental procedures. (Pediatr Dent 14:246-50, 1992)

Introduction

Hydrocephalus is an enlargement of the ventricularsystem, which results from an imbalance between pro-duction and absorption of cerebrospinal fluid (CSF)within the brain-fluid pathways.1 It is a pathologiccondition caused either by overproduction of CSF orobstruction in the aqueducts connecting the ventricles.There may be passive ventricular enlargement result-ing from loss of surrounding brain tissue due to agingor cerebrovascular accident, abnormal development ofthe cisterna magna and its connections over the brainsurface, or insufficient CSF circulatory absorption causedby failure of either villi function or venous drainage ofarachnoidal spaces.2

The incidence of hydrocephalus alone has been esti-mated as 0.48/1000 total births. 3 The total incidence ofhydrocephalus in association with other disorders, suchas spina bifida, has been reported as 1.33/1000 totalbirths.1

Ventriculoatrial (VA) shunts connecting the lateralventricles with the venous circulation were used widely,until they were supplanted by ventriculoperitoneal (VP)shunts. VP shunts empty CSF directly into the abdomi-nal cavity, thus bypassing the venous circulation. It isnow generally believed that patients with VP shunts areless likely to suffer serious morbidities, particularlythose associated with shunt infection (SI), than are pa-tients with VA shunts.4, 5

Shunt infections are costly in terms of morbidity,human suffering, intellectual and neurologic deficits

and health care funds.3 The incidence of SI has beenreported to range from 5 to 31%, with mortality ratesranging from 34 to 40%. SI is most likely to occur in thefirst postoperative month.7

It has been suggested that oral and nasopharyngealsources of staphylococci play a potential role in shuntinfections, 8 but no shunt infections have been relateddirectly to dental procedures. However, VA shuntshave been assigned a "high relative risk rate forbacteremia-induced infections," while VP shunts havebeen classified as being of "moderate risk." High-riskpatients always require antibiotic chemoprophylaxis,but the need for antibiotic chemoprophylaxis for mod-erate risk patients is controversial, and consultati6nwith a child’s physician is required before dental treat-ment.9

The purpose of this study was to investigate therelative risks assigned to VA and VP shunts followingspecific dental procedures for bacteremia-induced shuntinfections, as defined by directors of pediatric dentistryand neurosurgery advanced educational programs.Additionally, the study sought to tabulate antibioticchemoprophylaxis recommendations for patients withhydrocephalus shunts.

Materials and Methods

A brief survey was mailed to directors of all accred-ited advanced educational programs in pediatric den-tistry and neurosurgery in the continental United States.

246 PEDIATRIC DENTISTRY: JULY/AuGuST, 1992 ~ VOLUME 14, NUMBER 4

The survey sought to investigate shunt prophylaxisrecommendations for VA and VP shunts based on pro-cedures performed. Also, information was sought onthe putative organisms of shunt infection, and the per-ceived risk of shunt infection following dental proce-dures.

Chi-square contingency testing was performed onthe dependent variable of shunt prophylaxis, based onprocedure performed and differences in responses be-tween pediatric dentists and neurosurgeons. Likewise,antibiotic recommendations were evaluated based onspecialty. Differences in the perceived risk of shuntinfection were evaluated using Student’s t-test. Rela-tive risk, a measure of individual respondent’s differentrecommendations for chemoprophylaxis based uponthe type of shunt, was evaluated using McNemar’s test.

ResultsSurveys were returned by 70.6% (N = 51) of all pedi-

atric dental program directors. Neurosurgery directorsreturned 61.9% (N = 63). There was no significant differ-ence in study compliance.

Shunt Prophylaxis Recommendations (Table 1)

VA ShuntsExcept for "invasive oral surgery procedures," pedi-

atric dental directors were significantly more likely torecommend chemoprophylaxis for routine dental pro-cedures for these patients. Pediatric dentist andneurosurgeon respondentsagreed, with near unanimity,that invasive oral surgicalprocedures warranted anti-biotic prophylaxis. Pediatricdental respondents, however,unlike their neurosurgerycounterparts, were equallyunanimous in recommendingantibiotic prophylaxis forroutine restorative dentalprocedures and scaling/rootplaning.

VP ShuntsThere were no significant

differences in the incidenceof antibiotic prophylaxis rec-ommendations for these pa-tients. More than 50% of re-spondents recommendedprophylaxis followinginvasive oral surgery proce-dures and extractions.

Organisms Responsible for Shunt Infection

Most of the neurosurgery directors (92.3%) believedthat staphylococcal organisms were most likely respon-sible for VA shunt failure, compared to 36.1% of pediat-ric dental directors (P < 0.001). When VP shunts wereconsidered, 84.6% of neurosurgeons believed thatstaphylococcal organisms were responsible for shuntinfection, compared to 33.3% of pediatric dentists (P 0.001). Pediatric dentists were significantly more likelyto believe that streptococcal organisms were respon-sible for shunt failure due to infection.

Recommended Antibiotic (Table 2)

Pediatric dentists were significantly more likely torecommend penicillin as the antibiotic of choice forboth VA and VP shunts, recommending it nearly 100%of the time. (P < 0.01 and P < 0.025, respectively).Although neurosurgery respondents were less likely torecommend penicillin, more than 60% did recommendpenicillin.

Relative Risk (Table 3, next page)

Relative risk is expressed in terms of the per cent ofrespondents recommending shunt prophylaxis for VAshunts, but not for VP shunts, for a specific procedure.

Neurosurgeons

With the exception of noninvasive dental prophy-laxis, neurosurgeons are significantly more likely torecommend shunt prophylaxis for VA shunts than for

Table 1. Antibiotic prophylaxis recommendations

VA Shunts VP ShuntsProcedure Pediatric Dentists Neurosurgeons Pediatric Dentists Neurosurgeons

Restorative 35 (97.2)° 19 (48.7) 12 (33.3) 9 (23.1)

Extractions 36 (100.0) 36 (92.3) 19 (52.8) 27 (69.2)

Prophylaxis 17 (47.2) 9 (23.1) 4 (11.1) 6 (15.4)Scaling 36 (100.0)t 17 (47.2)§ 19 (52.8) 20 (51.3)

¯ P< 0.001, Chi-square --- 17.27, 1 df; * P< 0.025, Chi-square = 6.25, 1 df.

§ P< 0.05, Chi-square = 4.82, 1 df.

Absolute count (percentage) recommending shunt prophylaxis for VA and VP shunts.

Table 2. Antibiotic of choice for shunt prophylaxis

VA Shunts VP ShuntsAntibiotic Pediatric Dentists NeurosurgeonsPediatric Dentists Neurosurgeons

Penicillin 31 (93.9)° 19 (63.3) 15 (100.0)t 19 (63.3)

Other 2 (6.1) 11 (36.7) 0 (0.0) 6 (27.3)

¯ P< 0.025, Chi-square -- 5.20, 1 df.

* P< 0.01, Chi-square = 7.53, 1 df.

Absolute count (percentage) recommending specific antibiotic, for those recommending prophylaxis.

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Table 3. Relative risk of shunt infection

Procedure Pediatric Dentists Neurosurgeons

Restorative 23 (65.7)" 10 (52.6)~

Extractions 17 (48.7)" 9 (25.0)~

Prophylaxis 13 (76.5)" 3 (33.3)

Scaling 17 (48.2)" 11 (35.5)"

¯ P < 0.001, McNemar test, 1 df, VA > VP.* P< 0.01, McNemar test, 1 df, VA > VP.For those recommending VA shunt prophylaxis, absolute number(percentage) not recommending prophylaxis for patients with shunts undergoing corresponding procedures.

VP shunts (P < 0.01). Changes in recommendation phi-losophy for extractions and noninvasive dental pro-phylaxis suggest a perception of high risk associatedwith extractions, and low risk associated with dentalprophylaxis.

Pediatric Dentists

Pediatric dental directors consistently believed thatshunt prophylaxis was more appropriate for patientswith VA shunts (P < 0.001)

Perceived Risk

VA ShuntsNeurosurgery directors believed that 3.0% (SD 0.026)

of infected VA shunts may have resulted from dentalprocedures. Pediatric dental directors, however, ascribed5.2% (SD 0.076) of infected VA shunts to dental proce-dures. (P < 0.05, t = 1.73, 45 df)

VP ShuntsNeurosurgery directors believed that 1.8% (SD 0.019)

of infected VP shunts may have resulted from dentalprocedures. Pediatric dental directors believed 2.8%(SD 0.063) of infected VA shunts were ascribed to dentalprocedures. (NS)

Discussion

Antibiotic prophylaxis to prevent infectiveendocarditis in susceptible patients undergoing invasivedental procedures has become an accepted standard ofcare, despite lack of controlled studies substantiatingeffectiveness or risk/benefit. Highly specific guidelineshave been promulgated and updated periodically.10

The need for antibiotic prophylaxis for thehydrocephalic dental patient with a surgically placedshunt is controversial. Few medical and dental studiesaddress either side of the issue; since Croll’s call formore definitive knowledge and research in this area,2

little has been added to the literature. Since Croll’sarticle, VP shunts have superseded VA shunts in theUnited States. However, the pediatric dentist treating

developmentally disabled patients is still likely to en-counter older individuals with VA shunts. This studyindicates nearly unanimous agreement that VA shuntsrequire antibiotic prophylaxis.

The current survey indicates dichotomies in manag-ing hydrocephalic shunt patients. In general, pediatricdental respondents were more aggressive in recom-mending antibiotic prophylaxis of shunts, particularlyVA shunts. This aggressive use of antibiotics beliestheir belief that dental procedures may be responsiblefor SI, although, overall, pediatric dental program di-rectors believed that less than 5% of all shunt infectionsresulted from bacteremias caused by dental procedures.This aggressive use of chemoprophylaxis is directedtoward streptococcal species and, accordingly, penicil-lin is recommended nearly universally. However, it isinteresting that the neurosurgery respondents, whilemore likely to ascribe shunt infection to staphylococcalspecies, still frequently recommended penicillin.Neurosurgery directors did recommend a significantlygreater variety of antibiotics, including dicloxacillin,trimethoprim/sulfamethoxazole (Bactrim , RocheProducts Inc., Manati, Puerto Rico), vancomycin,tobramycin, oxacillin, amoxicillin, ampicillin/gentamicin, and cephalexin.

The spectrum of microorganisms associated with SIis wide. Although most reports agree that Staphylococ-cus aureus (coagulase positive) and Staphylococcusepidermidis (coagulase negative) are the most commoninfective microorganisms,5, 8, 11 recovered bacterialpathogens have included diphtheroids, enterococci,klebsiella, and streptococci,5, 7 in addition to fungalpathogens.12 Although most SI occurs within the firstmonth of shunt placement and is caused by either S.aureus or S. epidermidis, introduced at the time of shuntplacement, the role of prophylactic antibiotics at thetime of shunt placement is equivocal and remains highlycontroversial. 7 The agents used most widely whenshunts are placed have been oxacillin, methicillin,dicloxacillin, and vancomycin, which are all effectiveagainst S. aureus and epidermidis.2, 6, 13

Several studies have indicated bacteremia in chil-dren following routine dental procedures. The inci-dence of bacteremia following dental prophylaxis hasbeen reported to be 28%, while bacteremias were re-ported in 63% of children undergoing extractions.14

The incidence of bacteremia following extractions per-formed after penicillin prophylaxis has been reportedto range from 21 to 35%.I5, 16 The microorganismsisolated following extractions or dental prophylaxishave included those capable of causing SI. 14-16 Al-though coagulase-positive and negative microorgan-isms have been reported in such isolates only infre-quently, the number of other penicillin-resistant strains

248 PEDIATRIC DENTISTRY: JULY/AUGUST, 1992 N VOLUME 14, NUMBER 4

isolated may be of concern.16 Moenning et al. 17 havesuggested the use of amoxicillin and potassiumclavulanic acid combinations (Augmentin , BeechamLabs, Bristol, TN) available for oral use or ampicillinand sublactam (Unasyn , Pfizer, Inc., New York, NY)for parenteral use to overcome the action of penicilli-nase, thus allowing beta-lactam antibiotics to be effec-tive. These preparations are effective against manystaphyloccocci, klebsiella, virtually all anaerobes, andoral streptococci.

Little evidence supports antibiotic prophylaxis forpatients with hydrocephalus shunts following dentalprocedures. Respondents believed that dental proce-dures were related only infrequently to subsequentshunt infection, but they clearly perceived a hierarchyof risk, based both upon shunt type and procedureperformed. VA shunts are considered to be at higherrisk for SI, based upon the greater frequency of antibi-otic prophylaxis recommendations. However, antibi-otic prophylaxis also is recommended frequently forpatients with VP shunts, particularly when extractionsor scaling/root planing are performed. The low risk ofSI related to dental procedures is perhaps reflected inthe lack of coherent approach to chemoprophylaxis.The philosophical approach to shunt prophylaxis iscomplex. Penicillin resistant organisms are associatedpredominantly with SI, but it is not known whetherthey exist in sufficient number and virulence in themouth to colonize shunts. The bacteremias that followdental procedures typically are responsive to penicillin.In general, for those infections or procedures producingbacteremia that ordinarily are responsive to penicillin,the selection of a penicillinase resistant antibiotic isdeferred until the primary antibiotic is shown to beineffective, or until sensitivity testing confirms penicil-lin resistant organisms.

An inherent quandary exists. When faced with SI,the neurosurgeon aggressively administers a penicilli-nase-resistant antibiotic, and often must replace theinfected shunt.7 Should we risk development of organ-isms resistant to penicillinase-resistant antibiotics be-cause of their prophylactic use, particularly when thepresence of these microorganisms in the oral cavity is solow, and unlikely to colonize and infect shunts? Thismay explain why neurosurgeons are still very likely torecommend penicillin for shunt chemoprophylaxis.Reserving the use of penicillinase resistant antibioticsfor actual shunt infections, rather than for postshuntplacement prophylaxis, appears to be a strategy usedby neurosurgery program directors.

Croll et al. 2 recommended using dicloxacillin forprocedures that may cause gingival hemorrhage. Only13.3% of neurosurgery directors recommending pro-phylaxis advised using dicloxacillin for patients with

VA shunts undergoing extractions. For patients withVP shunts or undergoing other procedures, dicloxacillinwas recommended less often.

Definitive knowledge concerning shunt prophylaxisis lacking. An understanding of the organisms involved,drug sensitivities, and a risk/benefit assessment forantibiotic prophylaxis is necessary to formulate a coher-ent approach to manage hydrocephalus shunt patientsundergoing dental procedures. This coherent approachmust be based on an investigation of the incidence of SIfollowing dental procedures, and a dialogue betweenpediatric dentists and neurosurgeons in their mutualadvocacy for patient health.

Conclusions1. Shunt infection is considered an infrequent con-

sequence of dental treatment, although pediatricdentists are significantly more likely to believethat VA shunt infections may be due to anteced-ent dental procedures.

2. Antibiotic prophylaxis is recommended morefrequently for VA shunts, particularly by pediati

ric dental program directors.3. Extractions and scaling/root planing are per-

ceived to be higher risk procedures, by bothpediatric dentists and neurosurgeons, regard-less of shunt type.

4. Pediatric dentists are significantly more likely tobelieve that streptococcal species are responsiblefor SI following dental procedures, whileneurosurgeons ascribe SI to staphylococcal or-ganisms.

5. Penicillin is the antibiotic most commonly rec-ommended for shunt prophylaxis by both pedi-atric dentists and neurosurgeons, althoughneurosurgeons are significantly more likely torecommend an antibiotic other than penicillin.

Dr. Acs is assistant professor of Pediatric Dentistry and Pediatrics,Albert Einstein College of Medicine and director, Division of Pediat-ric Dentistry, Montefiore Medical Center, Bronx, NY. Dr. Cozzi is aresident at Montefiore Medical Center. Reprint requests should besent to: Dr. George Acs, Division of Pediatric Dentistry, MontefioreMedical Center, 111 East 210th Street, Bronx, NY 10467.

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